Last modified: December 2023

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AHELP for CIAO 4.16 Sherpa


Context: data


Unpack a FITS binary file into a data structure.


unpack_table(filename, ncols=2, colkeys=None, dstype=Data1D)

ncols - int, optional
colkeys - array of str, optional
dstype - optional


Example 1

Read in the first two columns of the file, as the independent (X) and dependent (Y) columns of a data set:

>>> d = unpack_table('sources.fits')

Example 2

Read in the first three columns (the third column is taken to be the error on the dependent variable):

>>> d = unpack_table('sources.fits', ncols=3)

Example 3

Read in from columns 'RMID' and 'SUR_BRI':

>>> d = unpack_table('rprof.fits', colkeys=['RMID', 'SUR_BRI'])

Example 4

The first three columns are taken to be the two independent axes of a two-dimensional data set ( x0 and x1 ) and the dependent value ( y ):

>>> d = unpack_table('fields.fits', ncols=3,
...                  dstype=Data2D)

Example 5

When using the Crates I/O library, the file name can include CIAO Data Model syntax, such as column selection. This can also be done using the `colkeys` parameter, as shown above:

>>> d = unpack_table('rprof.fits[cols rmid,sur_bri,sur_bri_err]',
...                  ncols=3)


The parameters for this function are:

Parameter Definition
filename Identify the file to read: a file name, or a data structure representing the data to use, as used by the I/O backend in use by Sherpa: a tablecrate for crates, as used by CIAO, or a list of AstroPy HDU objects.
ncols The number of columns to read in (the first `ncols` columns in the file). The meaning of the columns is determined by the `dstype` parameter.
colkeys An array of the column name to read in. The default is none .
dstype The data class to use. The default is `Data1D` and it is expected to be derived from `` .

Return value

The return value from this function is:

The class of the returned object is controlled by the `dstype` parameter.


See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

dataspace1d, dataspace2d, datastack, fake, load_arf, load_arrays, load_ascii, load_bkg, load_bkg_arf, load_bkg_rmf, load_data, load_grouping, load_image, load_multi_arfs, load_multi_rmfs, load_pha, load_quality, load_rmf, load_staterror, load_syserror, load_table, pack_image, pack_pha, pack_table, unpack_arf, unpack_arrays, unpack_ascii, unpack_bkg, unpack_data, unpack_image, unpack_pha, unpack_rmf
get_default_id, list_bkg_ids, list_data_ids
add_model, add_user_pars, load_table_model, load_template_interpolator, load_template_model, load_user_model, save_model, save_source
save_arrays, save_data, save_delchi, save_error, save_filter, save_grouping, save_image, save_pha, save_quality, save_resid, save_staterror, save_syserror, save_table